The present invention relates to a device for breaking nicks connecting two edges of a cutting line which is provided on blanks of cardboard before folding them, comprising a frame carrying means for conveying the blanks along a path substantially planar and two parallel shafts, rotatably mounted on both sides of the plane of the path, comprising tools for inducing a shearing between the edges adjacent to the cutting line, during their displacement, in order to break the nicks.
When cutting certain cardboard blanks to be folded according to folding lines, to form boxes in particular, it is often useful or even necessary, to maintain a connection between the adjacent edges of at least some cutting lines, in order to avoid that the blanks cling to one another. Generally, these are punctual connections between the edges of the cutting line and spaced from one another along the cutting line.
When introducing such blanks into a folder-gluer, these connections must be broken before performing the folding operations of these blanks.
A device has already been proposed, for example, in patent EP 0 680 821. This device is more particularly intended to break the fibers of cardboard which can accidentally remain in blanks from which the various panels are separated by simple cutting lines. Even if the reasons of the connections are involuntary here, the problem to be solved is, however, completely comparable with that evoked above.
The solution suggested by the above-mentioned document has a plurality of disadvantages, primarily related to its lack of flexibility, the tools for inducing the shearing in order to break uncut fibres being directly formed on the rotary shafts. Therefore, the change of the type of cardboard blanks requires the change of the two shafts, involving a significant disassembling operation of the device. Moreover, the swivel pins of these shafts on the frame being fixed, such a device can only be used for a same type of box, in this case cigarette packagings, so that this device is not usable to process cardboard blanks of substantially different sizes.
Another disadvantage, related to this solution of prior art, lies in the fact that the cardboard blanks must be spaced from one another with very precise spacings, or else, if the relative position of the tools and blanks varies, there will be a shift between the tools and the parts of the cardboard blanks to be worked, making it impossible to achieve the goal required and being likely to damage the cardboard blanks. However, the keeping of this precise spacing requires adjustment operations which are long and meticulous so that the productivity is limited, owing to the fact that the number of blanks processed per unit of length cannot be optimized.
The aim of the present invention is to meet, at least partly, the difficulties of the above-mentioned device.
To this end, this invention is directed to a device which comprises a frame, a conveyor supported by the frame for conveying cardboard blanks along a path that is substantially planar, first and second parallel shafts rotatably mounted to the frame and disposed on both sides of the substantially planar path of the blanks, first and second annular tool supports respectively disposed on the first and second shafts, a mechanism operative to move the tool supports both rotatively and linearly on the first and second shafts to position the tool supports both angularly and longitudinally on the respective shafts, first and second shearing tools respectively supported on the tool supports, whereby the shearing tools are rotatable with the respective shafts, and a drive mechanism for rotating the shafts and the tools thereon.
The design of this device allows a great flexibility of use and an adaptation to cardboard blanks of sizes likely to vary in significant proportions. This new design also facilitates the adjustment of the position of the tools, thus increases the productivity.
Numerous other particularities and significant advantages of this device will become evident from the following description and from the enclosed drawings which illustrate, schematically and by way of example, an embodiment of the device for breaking the nicks connecting two edges of a cutting line, object of the present invention.